feat: add final verification screen capture and update response structure

tests/test_agent_tools.py

@@ -67,8 +67,13 @@ def test_task_complete_captures_return_and_data(tmp_path: Path, monkeypatch) ->
     assert result["ok"] is True
     assert result["return"] == "Task completed successfully"
     assert result["data"] == "file1\nfile2"
+    assert result["verification"]["ok"] is True
+    verification_path = Path(result["verification"]["path"])
+    assert verification_path.exists()
+    assert verification_path.name.startswith("screen_final_verification_step_")
     assert agent.final_result == "Task completed successfully"
     assert agent.final_data == "file1\nfile2"
+    assert agent.final_verification is not None
 
 
 def test_click_supports_directional_offsets(tmp_path: Path, monkeypatch) -> None: